This invention relates to a method and an apparatus for checking the fitness of value documents, such as e.g. bank notes, checks, tickets, . . . . A fitness check for the purposes of the present application is understood to mean the check of used value documents for their fitness for circulation, e.g. of bank notes being in circulation, on the one hand, but also the quality check of new value documents after their manufacturing and before they go into circulation, e.g. the quality check of freshly printed bank notes, on the other hand.
For the fitness check of value documents it is known to check the value documents with the aid of sensors and to compare the fitness measurement values picked up with threshold values, in order to differ between value documents which are fit for circulation (fit), not fit for circulation (unfit), and if required further fitness classes, such as e.g. ATM-fit. It is necessary here that a user of the apparatus carrying out the fitness check, e.g. an operator, an adapteur or a service person of the apparatus, selects and defines suitable threshold values for the sensors. Then these defined threshold values serve to classify the value documents to be checked into value documents fit for circulation and not fit for circulation with the aid of a value-document processing apparatus, and to sort the value documents, for example, into different output pockets of the value-document processing apparatus.
A disadvantage with the known methods is that it is complicated for the user to define suitable threshold values for the sensors. Here, for example threshold values already specified by the manufacturer of a value-document processing apparatus, which are fixedly specified, are assumed. Problems are caused here e.g. by aging or soiling of the value-document processing apparatus or by changes, e.g. aging, of the value documents to be processed in the course of time. If one or several of the threshold values are defined only slightly too high by the user, value documents that are actually no longer fit for circulation are categorized as fit by the bank note processing machine. If, however, one or several of the threshold values are defined only slightly too low by the user, value documents that are actually fit for circulation are categorized as unfit by the bank note processing machine. Thus, the value documents to be processed are not sorted into fit and unfit value documents in the manner desired by the user.
Furthermore, it has hitherto not been taken into account sufficiently that many fitness measurement values contribute to the fitness of the particular value document. It may thus occur that several fitness measurement values respectively are slightly below their threshold values and the relevant value document is categorized as fit, although a human viewer would categorize it—by all appearances—as unfit. Many fitness measurement values also lead to the fitness check becoming hardly manageable for a user of the apparatus for the fitness check—on account of the plurality of threshold values that are necessary therefor. If the user wants to change the severity of the fitness check, e.g. to tighten it, he has to change a plurality of parameters.